Hydrogenated Oxide Material for Self‐Targeting and Automatic‐Degrading Photothermal Tumor Therapy in the NIR‐II Bio‐Window

Abstract Developing photothermal agents (PTAs) for tumor therapy has three prerequisites: selectively targeting tumors, efficiently converting near‐infrared (NIR) photoenergy to heat, and degrading after the cure. These make up a combination rarely found in one material. Here a metal‐acid treatment is reported to hydrogenate metal oxide, bestowing the produced H x MoO 3 with metal‐like electronic structure which enables harvesting NIR‐II light (1000−1350 nm wavelength). Importantly, created by putting acid protons into oxide, the H x MoO 3 nanomaterial can resist attacking from protons in acids but is vulnerable to hydroxyl ions in alkaline. After entering biological organism, H x MoO 3 PTAs persist long in acidic tumor microenvironment (TME, extracellular pH 6.5–6.9) while degrade quickly under the normal physiological environment (pH 7.2−7.4), naturally causing tumor‐selective accumulation. Under 1064 nm NIR‐II illumination, the H x MoO 3 achieves a high photothermal conversion efficiency of 60.9%, leading to a high tumor inhibition rate of ≈97.25%. Such a novel PTAs integrates merits of metal and oxide, opening a door of smart photothermal therapy with self‐adaptive tumor‐accumulation and automatic degradation after tumor hyperthermia.